Circuit breakers



March 15, 1955 1. w; cox 2,704,313

CIRCUIT BREAKERS Filed March 12, 1952 2 Sheets-Sheet 1 March 15, 1955 1. w. cox 2,704,313

CIRCUIT BREAKERS Filed March 12, 1952 2 Sheets-Sheet 2 United States Patent CIRCUIT BREAKERS Irvin W. Cox, West Allis, Wis., assignor to Cutlerl-Iammer, Inc., Milwaukee, Wis., a corporation of Delaware Application March 12, 1952, Serial No. 276,169

11 Claims. (Cl. 200-116) This invention relates to improvements in circuit breakers; and more particularly to circuit breakers subject to botlh manual control and automatic electro-thermal contro An object of this invention is to provide a circuit breaker utilizing an electro-thermal vapor pressure power element, which circuit breaker is extremely sensitive in respect of automatic operation thereof, easy and inexpensive to manufacture and assemble, while at the same time being of relatively small size.

Another object of this invention is to provide an electrothermal power element operated circuit breaker which is of substantially greater sensitivity than circuit breakers heretofore proposed and has smoother circuit breaking action.

' Another object of this invention is to provide an improved electro-thermal vapor pressure operated power element which may be readily associated with other elements to form a circuit breaker composed of a minimum number of separate parts.

Another object of the invention is to provide an electrothermal vapor pressure operated power element which is relatively inexpensive to make and charge and which is unusually sensitive to changes in electric current passing therethrough.

To attain certain objects of this invention I provide a power element constructed from a thin metal sheet which is folded upon itself to provide two adjacent walls. Intermediate the ends of the member thus formed, a diaphragm is made by a continuous weld passing around an area enclosed thereby. The walls of the element extend from opposite edges of the diaphragm to form supports by which the element becomes a movable currentcarrying part of a circuit breaker. It is desirable both for heat dissipation and to facilitate welding that a portion of the walls immediately adjacent and exterior of the welded seam be spaced to provide an air gap therebetween which will more readily dissipate electro-thermal heat outside of the diaphragm and cause apparent concentration thereof at the diaphragm. At the time of making the continuous weld the diaphragm may be charged with a predetermined amount of water either in liquid or vapor state. Other types of vaporizable charges may be used in place of water.

The power element so constructed is flexibly associated with a terminal and carries a movable contact which engages with and disengages from a fixed contact. The power element thus performs as a conductor, a mechanical lever for carrying a contact, and a power element. A spring-biased kick-out member is pivotally associated with the power element to normally flex it in a direction to open the contacts. A keeper and latch lock the kick-out member with the contacts closed. The keeper is connected with the kick-out member so that the expansion of the power element disengages the keeper from the latch to unlock the kick-out member. By arranging the power element so that it flexes in the plane of the diaphragm considerable space is conserved and efliciency increased by the resulting simplification of motion transmission elements.

A vapor pressure type electro-thermal power element broadly similar to that herein disclosed, and adapted for the tripping of circuit breakers, is shown in my prior U. S. Patent No. 2,484,932, dated October 18, 1949.

The novel features, which are considered characteristic of the invention, are set forth with particularity in p "ice the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of a specific embodiment when read in connection with the accompanying drawings in which:

Figure 1 is a view in side elevation of a circuit breaker embodying the present invention with the cover to the housing removed. However, in order to show the relationship between the G-spring and cams on the cover such cams are shown in broken lines as if the cover was in p ace;

Fig. 2 is a sectional view taken on line 22 of Fig. 1 showing the diaphragm collapsed and the circuit breaker latched with contacts closed;

Fig. 3 is a fragmentary view in side elevation of the power element removed from the circuit breaker;

Fig. 4 is a sectional view similar to the view of Fig. 2 and taken on line 2-2 of Fig. l with the diaphragm expanded and the circuit breaker unlatched and the contacts open;

Fig. 5 is a top plan view of the power element and its mounting terminal and movable contact all removed from the circuit breaker; and

Fig. 6 is a view in side elevation of the inside of the cover for the housing showing the recess which forms the cams for the G-spring, such spring being in the Off position after being reset.

The circuit breaker disclosed in the drawings includes a housing, a flexibly mounted power element functioning as a conductor and contact carrier, :1 spring-biased kickout member to move the circuit breaker to open position, and a keeper and latch normally locking the circuit breaker in closed position and discngageable by the expansion of the diaphragm of the power element, and a manually operable control member for resetting the circuit breaker with a snap action. Each of these elements or sub-combinations thereof will be hereinafter described in particular and their respective co-functional relationship described. The housing consists of a base 8 and cover 10 of insulating material each adapted to be produced by a straight line molding operation. The base 8 is recessed to provide operating space for the circuit breaker and has grooves and projections cooperating with the cover 10 to secure the fixed elements of the circuit breaker. The cover 10 is secured to the base 8 by suitable fastening means and also has conformations cooperating with the base 8 to provide guides for the movable elements and supports for the fixed elements. As shown in Fig. 6, the cover 10 has a depression which forms cam surfaces which cooperate with the C-spring to provide for snap closing or opening of the circuit breaker.

Power element The power element designated generally at 12 functions as: a conductor in the circuit-breaking mechanism, a support for the movable contact, a lever through which the spring-biased kick-out member functions, and also the means for supplying electro-thermal power for unlatching the kick-out member. Such power element is made from a ribbon or sheet of thin metal such as stainless steel (other suitable metals may be employed) which is preferably folded about a central line or bight as at 18 (see Fig. 5) to form Wall 14 and an opposed Wall 16. Spaced from the ends thereof each wall is formed with an inwardly biased disc-like area 20 surrounded by an annular portion 22. These annular portions 22 are in surface contact and a continuous seam weld joins such contacting surfaces to define a diaphragm. The walls 14 and 16 of the diaphragm are normally urged inwardly into approximate contact with each other substantially centrally thereof. Said walls 14 and 16 return, with a snap action, to normal position upon a predetermined decrease in internal pressure, after operating expansion of the diaphragm. The portions of walls 14 and 16 immediately adjacent the exterior of rings 22 are spaced from each other to provide air gaps 26, 26 (see Fig. 5) so that heat generated in said walls by the passage of electric current therethrough will be readily dissipated from both surfaces of the walls at such gaps. Such construction limits the area short-circuiting the seam-weld at the time of welding, and thus facilitates welding.

At the time the continuous seam weld is made the diaphragm is charged or filled. The charge may be a suitable vaporizable material, the amount of which may be determined in a variety of ways. For example, a drop of water of accurately controlled volume may be inserted within the diaphragm just before the welding pressure and heat are applied. In another example, the weld may be made in a vapor atmosphere such as steam atmosphere. The amount of steam entrapped in the diaphragm will always be fixed by the predetermined cubic capacity of the diaphragm and the temperature, pressure, and saturation of the steam atmosphere. Other types of vaporizable fill may be used, and as described in the aforesaid pateut the power element will be subjected to sharp expansive force at the boiling point of the fill or at a few degrees rise above such boiling point.

The power element 12 is mounted so that it will flex in the plane of the diaphragm to permit said element to act as a lever and as the carrier for the movable contact. To accomplish this a mounting terminal 28 is secured to one end of the power element and held in the housing by the cooperation of the base 8 and cover 10. It is preferable to have a slot 30 (see Fig. in the mounting terminal into which the ends of walls 14 and 16 are fitted and secured by welding, as indicated at 32, 32. A binding screw 34 or other suitable fastening device may be used to connect the mounting terminal 28 to an electrical conductor. Between the diaphragm and the mounting terminal 28 the walls 14 and 16 are provided with a racktype pleat 36. This pleat will flex to provide for movement of the power element 12 in the plane of the diaphragm.

The other end of the power element has secured thereto a support 38 for the movable contact. This support, like the mounting terminal 28, has a slot 40 into which the bight 18 is fitted and secured by a weld, as indicated at 42, 42. The support 38 carries the movable contact 44 which engages With and disengages from a fixed contact 46 carried on a fixed support and terminal member 48. This latter member is held in place by the cooperation of the base 8 and cover and carries a binding screw 50 or other-suitable fastening by which it may be connected with an electrical conductor.

Thus when the contacts 44 and 46 are engaged the current flows through the walls 14 and 16 of the power element 12. When an overload occurs enough additional heat will be generated to effect expansion of the diaphragm with a snap action from the normal or collapsed position shown in Fig. 2 to the expanded position shown in Fig. 4. In order that this lateral expansion of the power element may be utilized to trip a latching mechanism, the central part of the diaphragm is provided with integral projections 52 fitting into annular openings at the inner ends of inwardly extruded portions 58, 58 on the legs 54 and 56 of the kick-out member a portion of which forms one element of a snap-on type pivotal connection between power element 12 and the kick-out member. The edge of each socket engages the adjacent wall of the diaphragm to provide a small area of contact between the diaphragm and the kick-out member to minimize the amount of heat conducted away from the power element and thus insure maximum sensitivity.

Kick-out member and latch mechanism In order to provide a snap action opening of the contacts 44 and 46, a spring-biased kick-out member is pivotally connected to the diaphragm of the power element assembly 12 to normally urge it in a vertical direction. The kick-out member is locked in compressed position with such contacts closed by a latching mechanism which is unlatched by the expansion of the diaphragm.

To conserve space and weight and for cheaper manufacture the kick-out member includes as one integral unit the kick-out spring and keeper. A sheet or ribbon of thin metal, preferably stainless steel, is folded to provide a pair of legs 54 and 56 (see Figs. 2 and 4) which straddle the diaphragm of power element 12. As previously described each of these legs is provided with a socket 58 which provides a snap-on pivotal connection between the power element 12 and the kick-out member. The leg 54 at its lower end is multiple-reflexed to form a spring 60, the lower end of which rests on the bottom of the base 8 and normally resiliently urges the kick-out memher and the power element 12 in a vertical or upward direction tending to open the contacts 44 and 46. At the top of the spring 60 the leg 54 has a projection 62 constituting the keeper of the latching mechanism. When the diaphragm of power element 12 is collapsed, the keeper 62 is engaged by latch portion 66 of a C-shaped spring 70 to keep the contacts closed, as shown in Figs. 1 and 2. The lower portion of the leg 56 is provided with a slot 64 to accommodate the latch portion 66 and permit the kick-out member to move up and down without displacing such latch portion. It may be advisable to strengthen the legs 54 and 56 by lateral flanges on their sides. There is provided a slot 65 in the right-hand reflexes of the spring 60 to provide clearance for the latch portion 66 and for the lower end of the leg 56 when such spring is compressed. However, in some constructions it is possible to shorten the length of the folds of such spring so that there never is an overlapping relationship between the right-hand reflexes and such latch and leg.

The kick-out member is normally biased so that its legs 54 and 56 are sprung toward each other with suflicient force to maintain proper bearing contact at the snap-on pivotal connections when the diaphragm is collapsed. However, the diaphragm develops sufficient power to flex such legs apart against their inherent resiliency and against any resistance to lateral displacement created by the spring portion 60. In order that the keeper 62 will move to the left to the position shown in Fig. 4 as the diaphragm expands, the flanged leg 56 slides against the inside of the cover 10. Thus the expansion force supplied by the diaphragm of power element 12 must cause the leg 54 and the keeper 62 to move to the left relative to such cover and the latch portion 66 to disengage the keeper and latch. Vertical guides 68 may be formed on the base 8 to hold the kick-out member to reciprocating movement in a vertical path. Such guiding of the kickout member will also have the secondary effect of guiding the power element 12 so that it moves in a path with the contact 44 in proper alinement with contact 46.

Manual control and reset device After overload conditions have caused an unlatching of the keeper 62 and latch portion 66 with the consequent snap opening of the contacts 44 and 46 by the operation of kick-out spring 60, it is necessary to manually reset the latching mechanism in order to snap the contacts to closed position. To accomplish this. a C-spring 70 and manual control lever 74 are used. The lower end of 6- spring 70 is inturned to constitute the latch portion 66 and the upper end is inturned and fits within a hole 73 in the control lever 74 to provide a connection therebetween. This hole, upon the operation of the control lever, is moved clockwise from the position shown in Fig. l to a position substantially ninety degrees there from. During such movement, the ends of the C-spring 70 pass over a dead center alinement with respect to the axis of rotation of the control lever. The C-spring is slidably guided within a depression 76 formed in the inner surface of the cover 10 and shaped as shown in Fig. 6. The outline of this depression is also shown in broken line in Fig. 1 to show the camming action between such depression and the C-spring. The depression 76 has a concave edge forming a cam 78 which is engaged by the body of the C-spring 70 to cause the latch portion 66 to be moved upwardly toward and into a reset notch 80 in such depression as the control lever 74 is moved clockwise to the Reset position. The depression 76 has a convex edge 82 which atfords clearance for C-spring 70 during movement of the lever 74 in a counter-clockwise direction to the On position. In moving lever 74 to the On position from Reset position the G-spring 70 is moved with a snap action with suflicient force to overcome the force of the kick-out spring 60 and the inherent bias afforded by the pleats 36 of the power element 12 to effect closure of the contacts 44 and 46 with a snap action.

The control lever 74 is rotatably mounted by trunnions 84 mounted in bearings 86 in the base 8 and cover 10 and may be readily assembled and disassembled when the cover 10 is removed. It has a flat surface 88 which, when engaged by the top of the kick-out member when unlatched, will cause the control lever 74 to rotate to the Trip position shown in the dotted lines of Fig. 1 to constitute a visible indication that the circuit breaker has been tripped open by an overload.

Operation Starting from the On position shown in Fig. 1 a sequence of operations will be described. In the On position current is flowing from the terminals 28 and 48 through the power element assembly 12. If the circuit breaker becomes overloaded (due to flow of current exceeding the value for which diaphragm of power element 12 was calibrated) the increased electro-thermal heat generated by such excess current will vaporize the charge in the diaphragm and cause it to expand to the position shown in Fig. 4. Such expansion spreads the legs 54 and 56 and moves the keeper 62 out of engagement with the latch portion 66 permitting the spring 60 to move the kick-out member and the power element upwardly to the broken line position shown in Fig. 1, thus opening contacts 44 and 46 and breaking the circuit. The disengagement of thelatch portion 66 causes the C-spring 70 to assume a relatively free position (neither compressed nor tensioned) so that as the top of the kick-out member strikes the flat area 88 the control lever 74 will be moved to the Trip position shown in broken lines of Fig. 1.

While the diaphragm of power element 12 remains expanded it is impossible to close the circuit breaker because the latch 66 will not engage keeper 62. However, upon the opening of the circuit breaker the charge in the diaphragm quickly cools and the diaphragm will collapse to the position shown in Fig. 2 and the device after resetting may again be closed. To manually reset the circuit breaker the control lever 74 is moved clockwise to the Reset position. This raises the C-spring 70 and its latch portion 66. The intermediate portion of the 6- spring 70 engages the cam surface 78 and the latch portion 66 is forced into reset notch 80. When manual force is released from the control lever 74 the resiliency of the C-spring 70 will result in movement of such control lever counterclockwise to the Off position illustrated in Fig. 6 and indicated in Fig. 1. Thereafter the control lever 74, when moved counterclockwise from Otf position toward 0n position, compresses the G-spring 70, which coacts with cam surface 78 to cause the latch portion 66 to slide out of engagement with the notch 80 (see Figs. 1 and 6) and move with a snap action against the keeper 62 to efiect snap closure of the circuit. When the lever 74 is manually moved from On toward Off position the ends of O-spring 70 pass through the dead center with respect to the axis of rotation of the lever and the lever is moved ahead to Off position, thus relieving the tension in the C-spring to a degree sufiicient to permit the kickout spring portion 60 to act upon the portion 66 of C-spring 70, thus assisting said portion 66 in overcoming the resistance to upward movement thereof over angled surface 80 This results in snap movement of portion 66 into reset notch 80 and simultaneous movement, with a snap action, of contact 44 out of engagement with stationary contact 46.

Although I have shown a single embodiment of the invention, it is to be understood that the device is susceptible of embodiment in other forms without departing from the spirit of my invention as defined by the appended claims.

I claim:

1. Circuit breaker mechanism comprising a doublewalled member having one end fixed to a terminal, said member having a free end movable about said fixed end and carrying a movable contact, a fixed contact with which said movable contact engages to close a circuit through said member, spring means for biasing said member in a direction to open said contacts, said member including a diaphragm having a completely enclosed and sealed space between said walls and containing a material operable when heated to expand the walls of said diaphragm, a first latching element connected with said walls at said diaphragm, and a second latching element with which said first latching element engages to normally hold said member in a position to effect closure of said contacts, said first latching element being sprung by the expansion of said diaphragm to disengage from said second latching element.

2. Circuit breaker mechanism comprising a doublewalled member having one end fixed to a terminal, said member having a free end movable about said fixed end and carrying a movable contact, a fixed contact with which said movable contact engages to close a circuit through said member, spring means for biasing said member in a direction to open said contacts, said member including a diaphragm having a completely enclosed and sealed space between said walls and containing a material operable when heated to expand the walls of said diaphragm, a first latching element formed integrally with said spring means and connected with said walls at said diaphragm, and a second latching element with which said first latching element engages to normally hold said member in a position to effect closure of said contacts, said first latching element being sprung by the expansion of said diaphragm to disengage from said second latching element.

3. Circuit breaker mechanism comprising a doublewalled member having one end fixed to a terminal, said member having a free end movable about said fixed end and carrying a movable contact, a fixed contact with which said movable contact engages to close a circuit through said member, spring means for biasing said member in a direction to open said contacts, said member including a diaphragm having a completely enclosed and sealed space between said walls and containing a material operable when heated to expand the walls of said diaphragm, said member further having pleats between said diaphragm and said fixed end to permit said free end to move, a first latching element connected with said walls at said diaphragm, and a second latching element with which said first latching element engages to normally hold said member in a position to effect closure of said contacts, said first latching element being sprung by the expansion of said diaphragm to disengage from said second latching element.

4. Circuit breaker mechanism comprising a doublewalled member having one end fixed to a terminal, said member having a free end movable about said fixed end and carrying a movable contact, a fixed contact 'with which said movable contact engages to close a circuit through said member, spring means for biasing said member in a direction to open said contacts, said member including a diaphragm having a completely enclosed and sealed space between said walls and containing a material operable when heated to expand the walls of said diaphragm, a first latching element connected with said walls at said diaphragm, and a second latching element with which said first latching element engages to normally hold said member in a position to efiect closure of said contacts, said first latching element being sprung by the expansion of said diaphragm to disengage from said second latching element and including oppositely positioned inwardly biased mounting members, said walls at said diaphragm including mounting members interfitting with said first mentioned mounting members to pivotally interconnect said double-walled member and said first latching element.

5. Circuit breaker mechanism comprisinga doublewalled member having one end fixed to a terminal, said member having a free end movable relatively to said fixed end and carrying a movable contact, a fixed contact with which said movable contact engages to close a circuit through said member, spring means for moving said member in a direction to open said contacts, said member including a diaphragm having a completely enclosed and sealed space between said walls containing a material operable when heated to expand the walls of said diaphragm, a kick-out member having inwardly biased legs straddling said double-walled member and pivotally connected with said diaphragm, one of said legs having a keeper, and a latch for engaging said keeper to hold said circuit breaker closed, said keeper being moved out of engagement with said latch upon expansion of said diaphragm.

6. A circuit breaker as claimed in claim 5, in which there is a control lever, a second spring interconnecting said control lever and said latch and expansible and compressible by said lever, and camming means cooperable with said second spring to release said second spring when compressed whereby manual operation of said control causes said latch to engage said keeper with a snap action imparted by said second spring.

7. A circuit breaker as claimed in claim 6, in which said second spring is of substantially G-shape, said camming means comprising a stationary cam surface, and said snap action when etfected resulting in snap movement of said movable contact.

8. A circuit breaker as claimed in claim 5, in which there is a control lever having a seat, a second spring interconnecting said control lever and said latch and expansible and compressible by said lever, and camming means cooperable with said second spring to release said second spring when compressed whereby manual operation of said control causes said latch to engage said keeper with a snap action imparted by said second spring, said spring means when said second spring is uncompressed, as an incident to overload conditions, being strong enough to cause said kick-out member to engage said seat and swing said lever to a trip indicating position.

9. A circuit breaker comprising a power element including a thin double-walled diaphragm, a first terminal, said power element being flexibly mounted at one end to said first terminal whereby it has movement in the plane of said diaphragm, a movable contact carried by the other end of said power element, a second terminal, a fixed contact carried by said second terminal and engaged by said movable contact as said power element moves in one direction, a kick-out member having portions engaging the walls of said diaphragm at opposite sides of the latter and pivotally interconnected therewith, spring means associated with said kick-out member to normally urge said kick-out member in a direction to open said contacts, a keeper connected with said kick-out member, a latch adapted to engage said keeper to lock said kick-out member with said spring compressed and said contacts engaged, and manually operable control means for closing said contacts when said keeper and latch are engaged, said keeper being disengaged from said latch upon a predetermined degree of expansion of said diaphragm.

10. A circuit breaker comprising a power element including a thin double-walled diaphragm, a first terminal, said power element being flexibly mounted at one end to said first terminal whereby it has movement in the plane of said diaphragm, a movable contact carried by the other end of said power element, a second terminal, a fixed contact carried by said second terminal and engaged by said movable contact as said power element moves in one direction, a kick-out member having portions engaging the walls of said diaphragm at opposite sides of the latter and pivotally interconnected therewith, spring means associated with said kick-out member to normally urge said kick-out member in a direction to open said contacts, a keeper connected with said kick-out member, a latch adapted to engage said keeper to lock said kick-out member with said spring compressed and said contacts engaged, and manually operable control means for effecting closing or opening of said contacts when said keeper and latch are engaged, said keeper being disengaged from said latch upon a predetermined degree of expansion of said diaphragm whereby said circuit breaker is opened automatically.

11. A circuit breaker comprising a power element in cluding a thin double-walled diaphragm, a first terminal, said power element being flexibly mounted at one end to said first terminal whereby it has movement in the plane of said diaphragm, a movable contact carried by the other end of said power element, a second terminal, a fixed contact carried by said second terminal and engaged by said movable contact as said power element moves in one direction, a kick-out member having portions engaging the walls of said diaphragm at opposite sides of the latter and pivotally interconnected therewith, spring means associated with said kick-out member to normally urge said kick-out member in a direction to open said contacts, a keeper connected with said kick-out member, a latch adapted to engage said keeper to lock said kickout member with said spring compressed and said contacts engaged, manually operable control means for effecting closing or opening of said contacts when said keeper and latch are engaged, said keeper being disengaged from said latch upon a predetermined degree of expansion of said diaphragm whereby said circuit breaker is opened automatically, and said latch being operable by said control means after automatic opening of said circuit breaker to effect locking re-engagement of said latch with said keeper to thereafter provide for manual closing and opening of said circuit breaker.

References Cited in the file of this patent UNITED STATES PATENTS 1,670,697 Treanor May 22, 1928 2,221,670 Cooper Nov. 12, 1940 2,228,956 Helland Jan. 14, 1941 2,447,032 Shann Aug. 17, 1948 

